The present invention relates to improvements in switching mechanisms and particularly to a mechanism suited for controlling the circuits of a microwave oven.
In microwave ovens, existing standards established by practice, for optimum operation, and for safety reasons, require the precise and reliable control of a number of circuits. One of these circuits is the primary microwave circuit which normally is operated by separate switches which for safety reasons are connected in series so that both switches must be closed before the microprocessor will operate. Other switches which are employed are a light switch, a microprocessor timer switch and a monitor switch.
Convention and safety require that these switches must be sequenced in a controlled order in one direction when the door of the microwave oven is closed and in the opposite order when the door of the microwave oven is opened. When the door is open, the light switch is closed, the microprocessor timer switch is open, the monitor switch is closed and, of course, the primary microwave switches are open. When the door is closed, the light switch is opened, the two primary microwave switches are closed, the microwave timer switch is closed, and the monitor switch is opened. A control mechanism for these switches must be able to accomplish the foregoing switching operation, and additionally has other requirements for reliability and safety.
Of principal importance is the reliability and safety of the device and the switch operating mechanism must be capable of operating hundreds of thousands of repeated times without failure and be capable of being operated reliably so that with each opening and closing of the door, all switches are properly operated.
The durability, simplicity and reliability of the mechanical operating structure is essential both from the standpoint of safety and from the standpoint of reliability and avoidance of cost replacement. For this reason a structure is necessary which has parts having minimum travel, with such travel arranged to be most effective for the time when parts are in contact, and the parts simply and durably constructed. Ease of assembly is also important from the standpoint of avoiding any possibility of misassembly and from the standpoint of cost of the structure.
It is accordingly an object of the invention to provide an improved switching arrangement and switch operating mechanism which meets the above stated objectives and avoids difficulties encountered in structures heretofore available.
A further object of the invention is to provide an improved and simplified switch operating mechanism suitable for use in a microwave processing oven which is relatively inexpensive to construct yet is very reliable in operation.
A further object of the invention is to provide an improved reliable switching mechanism which is capable of operating in various environments but is particularly well suited for use in controlling the circuits of a microwave oven.
In accordance with the principles of the invention, a feature is the simplified arrangement of the switch leaves and the operating mechanism therefor. A case or housing is provided with one front wall removable and all elements including switch leaves, slides, cams and latches are insertable from one direction with all of the switch leaves projecting in one direction so as to be supported on one double end wall of the case. Further, control for switching purposes and safety arrangements is achieved through a latch and plunger which operate a slide and a cam both of which are slidably removable from the case for replacement. Also, the latch is provided with a hook to be held by a catch which is also slidably replaceable.